(一)利用绝对定位与transform
<div class="parent">
<div class="children"></div>
</div>
将父元素定位(relative),子元素如下
.children{
position: absolute;
top: 50%;
left: 50%;
-webkit-transform:translate(-50%,-50%);
background: black;
}
(二)利用flexbox
.parent{
justify-content:center;
align-items:center;
display: -webkit-flex;
}